Cementitious panel is one type of material used in the construction of buildings. One disadvantage to commonly used cementitious panel is that such panel possesses a high density and weight due to material composition. Commonly used cementitious panel is difficult to manage and use in the construction process due to its great weight per square foot. For example, standard cementitious board is approximately twice the weight per square foot of gypsum board.
Moreover, cementitious board used in the construction process may require a low permeability to increase the longevity of installation. Any introduction of additional ingredients to the composition of cementitious board may decrease durability such that the cementitious board does not pass required structural certification for use in construction.
The present invention relates to a cementitious panel comprised of a low density core surrounded by upper and lower facers of reinforcements embedded into the core or attached to it using cementitious slurry or adhesives. The core, the slurry or both can be made and/or enhanced with a low permeability to water (or water vapor) characteristic by adding ingredients to their respective compositions to achieve permeability values similar to or below those of type-15 bitumen treated felt paper.
More particularly, the present invention relates to panels or boards whose opposed broad faces are reinforced by a network of fibers which may be adhered at a surface thereof e.g. be adhered to or embedded at or just below the cementitious surfaces thereof and include a low density core using a light weight aggregate surrounded by cement paste to fuse the lightweight aggregate together. Still more particularly, the present invention relates to a cementitious board whose longitudinal edges are reinforced by a network of fibers. Such a cementitious panel or board may, for example, be a light-weight concrete panel, a tile backerboard panel, or the like.
The word “cementitious” as used herein is to be understood as referring to any material, substance or composition containing or derived from a hydraulic binder such as for example, Portland cement (see below), aluminate cement, and/or a pozzolan such as for example fly ash or blast furnace slag. The term “slurry” is to be understood as referring to a flowable mixture, e.g. a flowable mixture of water and one or more hydraulic binders and if desired or necessary, additional additives such as rheology modifiers, water reducers, chemical set control admixtures, and the like. The term “core” is to be understood as referring to a mixture of a hydraulic binders, water and aggregate (such as sand, expanded shale or clay, expanded polystyrene beads, slag and similar materials—see below), as well as, if desired or necessary, additional additives such as foaming agents, rheology modifiers, water reducers, and the like.
The term “slurry pervious reinforcing mesh” is to be understood as characterizing a mesh as being suitable for use in the preparation of a concrete panel by having openings sufficiently large to permit penetration of a cementitious slurry or a slurry component of a core mix, or a full core mix, into and through the openings so as to permit (mechanical) bonding of the mesh to the core either by for example by being cemented to the core or by being embedded in a face or surface of the core of a panel.
The expression “slurry impervious mesh” is to be understood as characterizing a mesh as being water impervious or as being able to filter out or inhibit the penetration of slurry or core solids therein so as to inhibit (mechanical) bonding of the mesh to the core by the cementitious material.
It is to be understood herein that the expression “adhered to” in relation to a reinforcing mesh component (e.g. mesh, mat, fabric, tissue, etc.) means that the mesh component may be adhered for example to a face or surface by any suitable means such as by an adhesive, by a binder, by a slurry, by a core, or by being embedded in, at or immediately beneath the surface of a respective face or surface such that the mesh component is effectively bonded to the core, i.e. a hardened or set cementitious material extends through the interstices of the fibrous layers.
Keeping the above immediate definition in mind, it is to be understood herein that the expression “adhered to said core at” in relation to a reinforcing mesh component (e.g. mesh, mat, fabric, tissue, etc.) means that the mesh component does not extend beyond the specified face, area, region, or the like, i.e. it is restricted to the specified face region etc. Thus for example in relation to a broad face reinforcing mesh indicated as being adhered to a core at a broad face means that the mesh is restricted to being adhered to the broad face.
The word “woven” as used herein is to be understood as characterizing a material such as a reinforcing fabric (e.g., mesh, tissue or the like) as comprising fibers or filaments which are oriented; oriented fibers or filaments being disposed in an organized fashion.
The word “non-woven” as used herein is to be understood as characterizing a material such as a reinforcing fabric (e.g. mat, tissue or the like) as comprising fibers or filaments which are oriented (as described above) or which are non-oriented; non-oriented fibers or filaments being disposed in random fashion.
In general, a reinforced cementitious panel or board may be fastened, or sometimes adhered, to a wall, or a wall frame, for the construction of a wall and particularly for the construction of a wall where high moisture conditions are to be encountered. Such a wall panel may provide a long lasting substrate for humid or wet areas such as shower rooms and bath rooms and provide high impact resistance where there is high number of people circulating. Exterior installations are also encountered. For example, such a reinforced cementitious panel or board may be used as a substrate for ceramic tile in bath rooms, shower rooms, locker rooms, swimming pool rooms and other areas where the wall are subject to frequent splashing of water and high humidity. For exterior installations, such a reinforced cementitious panel or board may be used as a substrate for a stucco wall system or a masonry veneer wall system. Once the panel is affixed to a wall frame a wall facing material may, as desired or necessary, in turn be affixed thereto such as, for example, ceramic tile, thin brick, thin marble panels, stucco or the like. Reinforced cementitious panels or boards having cores formed of a cementitious composition with the faces being reinforced with a layer of fabric bonded thereto are known; see for example U.S. Pat. Nos. 1,439,954, 3,284,980, 4,450,022, 4,916,604, etc. Further, cementitious panels or boards with reinforced edges are known; see for example, U.S. Pat. No. 6,187,409.
Various processes for the preparation of such cementitious boards or panels are also known. British Patent application No. 2,053,779 for example discloses a method for the continuous production of a building board which comprises advancing a pervious fabric on a lower support surface, depositing a slurry of cementitious material onto the advancing fabric, contacting the exposed face of the slurry with a second fabric such that the slurry penetrates through the fabric to form a thin, continuous film on the outer faces of the fabric.
Because of its cementitious nature, a cement board may have a tendency to be relatively brittle.
Cementitious wall board or panels are often attached at their marginal edges to the building framework with for example fasteners such as nails, screws and the like. When fasteners for example such as screws or nails are installed near the edge (less than ½), it is highly desirable that the edge be able to retain sufficient structural integrity such that the panel remains attached to a wall member, i.e. that the panel have a relatively high fastener pull resistance such that the fastener will not laterally pull through or break through the board edge easily.
It is known to augment the strength of the border edge regions by wrapping the fabric covering one broad face of the board around the edge so as to overlay the fabric on the other opposite broad side thereof
U.S. Pat. No. 4,916,004, for example, discloses a cement board having a woven mesh of glass fibers immediately below each face thereof, the mesh in one broad face continuing under the surface of both longitudinal edge faces, with the two meshes in an abutting or an overlapping relation along the longitudinal margins of the opposite face. Please also see U.S. Pat. Nos. 5,221,386 and 5,350,554.
U.S. Pat. No. 4,504,533, for example, discloses a gypsum board in which a composite web of a non-woven fiberglass felt and a woven fiberglass mat covers the upper and lower faces of a gypsum core while only the lower non-woven fiberglass felt is wrapped around the longitudinal edges of the gypsum core so that the non-woven fiberglass felt extends partially inward on the upper face of the core such that the border edge regions are covered only by non-woven fiberglass felt.
U.S. Pat. No. 1,787,163 on the other hand discloses a gypsum board in which side edge portions include a separate strip of U-shaped fabric extending from one broad face across the edge to the other broad face; the fabric legs of this separate strip each extend into the plaster core body beneath a respective sheet of fibrous material covering a respective broad face, i.e. the legs are submerged below the broad face and in particular below the broad face reinforcement means.
It would be advantageous to be able to have an alternate manner of making an alternative type panel configured such that when a nail, screw or like shaft fastener is inserted close to the edge of a panel the mesh reinforced edge may minimize edge break out by the nail or screw or like shaft fastener of edge and thus provide secure attachment of the panel to a framing support.
It would for example be advantageous to be able to customize the reinforcement characteristics of the longitudinal edge area of a panel by being able to choose a desired reinforcement mesh component which is different from the mesh used for the broad faces of a wall panel core and being able to choose a desired attachment technique to the longitudinal edge. It would be advantageous for example too be able to have a panel or board wherein the edge reinforcing mesh may be different from the broad face reinforcing mesh (e.g. of a different substance, of different mesh openings, of non-oriented fibers or filaments rather than oriented fibers or filaments).
It would be advantageous to be able to have a panel wherein the longitudinal edge face of the panel may be more or less free of cementitious material so as to allow the longitudinal edge face to be used as a support substrate for a visual indicia such as color, images, symbols, words, etc., i.e. such that an indicia would not be covered up during the manufacturing process by cementitious material.
It would be advantageous to be able to have a means of treating the side edges of the board in the course of manufacture in such a manner as to enhance its structural qualities and its use for the purposes intended. It in particular would be advantageous to be able to have a means of manufacturing the edges of the board in such a manner that it will have impact resistant edges and be able to be constructed so as to be able to offer a relatively higher lateral fastener pull resistance in the edge area than in the central core area or than a board not having such reinforced edges.
It would be advantageous to change the recipe for cementitious board to include at least one lightweight aggregate as to decrease the overall weight and density of the board while maintaining low permeability.